"Dale and the local police\u2019s investigation starts pointing directly to Ryn, meanwhile Xander and Calvin\u2019s search for Chris heats up when they locate the nurse who works at the military bunker."

"When Ben and Maddie attend his mother\u2019s fundraising gala, an unexpected guest shows up and offers to put an end to the overfishing that\u2019s threatening the lives of the mermaids in Bristol Cove."

"With more mermaids landing at Bristol Cove\u2019s shores, the threat of discovery increases. After his encounter with the siren song, Ben tries to cope with the after effects. Maddie\u2019s mom returns to town and tries to connect with her daughter. Meanwhile, Ryn attempts to adapt to life on land."

"Ben, Maddie and Ryn desperately try and keep the newly arrived mermaid pack hidden from the rest of the town, but the new mermaids\u2019 quick degradation on land forces them to get them back to the sea unnoticed during the town\u2019s Mermaid Beauty Contest. Elaine grows more suspicious of Helen and her connections to their family."

"Ryn fights to maintain leadership of the pack when the other mermaids question her loyalties. Ben interferes in a mermaid ritual causing friction between himself and Ryn, meanwhile, Helen discovers more about her family lineage."

"Ryn decides they need to find another solution for housing the mermaids, as hiding them becomes increasingly difficult. Ben becomes a mentor to Levi as he tries to learn how men behave on land, while Maddie continues to struggle with her mother\u2019s renewed presence in her life."

"Ryn continues to try to teach the other mermaids to be more human in order to better assimilate, but some are starting to resist her, causing Ryn to wonder if she herself is becoming too human. Maddie finds herself in a dangerous situation trying to help her mom. Meanwhile, Ben and Xander reconcile in order to work together to get the mermaid pack back into the water."

"Dale copes with the fallout from Maddie and Ryn\u2019s encounter with the man from Susan\u2019s past, while Katrina continues to persuade the rest of the mermaid pack to get on her side\u2014even if that means brute force against both mermaids and humans."

"Tensions are rising following a shocking discovery. And living in a tank rather than the ocean is starting to have an adverse effect on many of the mermaids. Hoping to save her kind, and help her human circle, Ryn makes a deal with a complicated ally."

"Mermaids and humans join forces in a radical plan to stop the oil company, but their efforts have a devastating effect. And facing an uncertain future, Ben, Maddie and Ryn come together for a romantic farewell."

"Ben, Maddie and the other humans deal with the fallout from the attack on the oil rig, while the mermaids reacclimate to their ocean home. Ryn comes back to land to follow through on an agreement she made with the military, despite not knowing what their ultimate goals are."

"With Elaine Pownall\u2019s health worsening, she seeks treatment from the military\u2019s medical trial using mermaid cells, but the procedure doesn\u2019t come without side effects to the mermaids. Meanwhile, Helen and Rick learn more about the hybrid status, their history in Bristol Cove, and discover they are far less alone than Helen once believed."

"Maddie and Ben contend with how to help Ryn knowing that in order to help Elaine get better, they will need to continue the procedures on Ryn. Meanwhile, when one of the group gets sirened, there is more drive than ever to get to the bottom of how the siren song really works\u2014further piquing the interest of the military in how Ryn can be of use to them."

"Ryn goes back to the ocean to get help for Ben and Maddie\u2019s conditions but discovers that continuing to go back may get harder than she realized the longer she\u2019s on land. But when they learn that there may be a special place in Ryn\u2019s homeland that could help them, Ben, Maddie and Ryn must all venture under the sea together to find the cure. Meanwhile, Helen and Ted connect over their shared family histories."

"Mermaid mating season has begun, with Ryn knowing she will need to go back to the sea to help her colony. The hybrids convince one of the mermaids to come with them to a remote location, leading Helen and Ben on a hunt to find them. A journalist turns to Xander for help putting the pieces together of the night of the oil rig disaster, but Xander is torn on where his loyalties lie and what helping him could mean for his future."

"Mating season turned out to be less successful than everyone had hoped, leading them to question the possibility of the mermaids procreating on land. Ryn brings a new mate ashore for the good of the colony, but it raises emotional questions for Ben and Maddie."

"Ben and Xander are left dealing with a shocking discovery about Chris and his connection to the military. Meanwhile, Helen and Maddie reluctantly seek help from the hybrids as the threat of extinction looms over the mermaids. Ryn encounters the journalist who continues to chase his theories on mermaids to increasingly desperate ends."